FIG. 8 illustrates a portion of a typical aircraft brake system 200 that includes a plurality of spaced, disk shaped stators 202 mounted on a torque tube 204 and a plurality of disk shaped rotors 206 that rotate with an aircraft wheel 207 and extend into the spaces between the stators 202. Pistons 208 are mounted on a piston housing 210 which is connected to the torque tube 204 by bolts 205. The pistons 208 apply pressure against a pressure plate 212 (the first stator in the stack of rotors and stators) to compress the stack, and the friction generated as the rotors are pressed into contact with the stators slows the aircraft wheel.
Each of the pistons 208 is mounted in a piston chamber 214 and biased into a retracted position relative to pressure plate 212 with springs 216. Hydraulic fluid flows into piston housing 210 through fitting 218 and into internal channels 220 formed in the aluminum piston housing 210 between the piston chambers 214. Thus, when pressure is applied to the fluid by an external source, (not shown) the pistons 208 are driven against the pressure plate 212; when the hydraulic pressure drops, the pistons 208 are retracted by springs 216.
It is known to replace various metal aircraft components with lightweight composite materials to reduce aircraft weight. Such weight reductions are generally desirable as they either save fuel or increase the carrying capacity of the aircraft. However, brake assemblies are subject to high temperatures and stresses. The rotors and stators can reach 1500° F. during a landing, and the hydraulic fluid pressure in the piston chambers and connecting hydraulic fluid lines can reach thousands of psi. Moreover, it is desirable to provide a suitably rigid piston housing because deformations of the piston housing can misalign the pistons 208 and piston chambers 214 and cause the pistons to bind, hydraulic fluid to leak, and/or the brake system to operate improperly. Aircraft brake assemblies, therefore, have not heretofore appeared to present good opportunities for weight reduction through the use of lightweight composite materials which generally cannot satisfy all the above requirements. It would, however, be desirable to reduce the weight of aircraft brake assemblies using composite materials if the aforementioned problems could be addressed.